I. FOREST
I.C.3.N.a. Mixed needle-leaved evergreen - cold-deciduous forest
I.C.3.N.a.32. TSUGA CANADENSIS - BETULA ALLEGHANIENSIS FOREST ALLIANCE
Eastern Hemlock - Yellow Birch Forest Alliance

Concept: This alliance is found in the Great Lakes region and the northeastern United States and can range as far south as the Southern Blue Ridge of North Carolina and Tennessee, where it can occur in high-elevation areas. Forests in this alliance are late successional upland forests, dominated by coniferous and deciduous trees. Tsuga canadensis and some combination of Acer saccharum, Betula alleghaniensis, and Fagus grandifolia are typically the dominant trees. Fagus grandifolia is not found in stands west of eastern Wisconsin. Associated trees include Acer rubrum, Betula lenta (in the eastern portion of this alliance's range), Carya spp. (in the south), Liriodendron tulipifera (in the south), Pinus strobus, Prunus serotina var. serotina (in the Allegheny Mountains), Quercus alba, Quercus rubra, and Ulmus americana. Picea rubens can be found in northern New England. The small tree Ostrya virginiana is often present in the subcanopy. In the northern portions of this alliance's range, the shade from the canopy and dense stands of Acer saccharum saplings and seedlings inhibits the growth of many other species. These stands often have depauperate ground layer strata. Where the shade is not as complete, shrubs such as Corylus cornuta, Diervilla lonicera, Hamamelis virginiana, Sambucus racemosa var. racemosa (= Sambucus pubens), and Viburnum lantanoides (= Viburnum alnifolium) may be found along with saplings of Abies balsamea and Picea glauca. In the southern portion of this alliance's range, ericaceous shrubs are common. Among these Kalmia latifolia, Rhododendron maximum, and Vaccinium pallidum are typically the most abundant. The herbaceous layer consists of species such as Anemone quinquefolia, Cornus canadensis (in the north), Dryopteris carthusiana (in the north), Epigaea repens, Maianthemum canadense, Medeola virginiana, Mitchella repens, Oxalis montana (in the east), Trientalis borealis (in the north), Trillium grandiflorum (in the north), and Viola spp. Stands of this alliance tend to be on dry-mesic to mesic loam and sand soils. The soil is sometimes acidic, especially in the southern portion of this alliance's range. The parent material is glacial till in the north and sandstone in the unglaciated southern part. Stands can be on flat to moderately steep slopes of any aspect.

Range: This alliance occurs in Michigan and northern and southeastern Wisconsin. It is widespread in the eastern United States in Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia, and West Virginia. It is also found in Canada from southern Ontario east to Nova Scotia, and in the Southeast in Tennessee and possibly North Carolina (?).

States/Provinces: CT MA MD ME MI NB NC? NH NJ NS NY ON PA RI TN VA VT WI WV

TNC Ecoregions: 44:C, 45:C, 46:C, 47:C, 48:C, 49:C, 50:C, 51:C, 52:C, 58:P, 59:C, 60:C, 61:C, 62:C, 63:C, 64:C

USFS Ecoregions: 212Aa:CCP, 212Ab:CCP, 212Ba:CCP, 212Bb:CCP, 212Ca:CCP, 212Cb:CCP, 212Da:CCP, 212Db:CCP, 212Dc:CCP, 212Ea:CCP, 212Ec:CCP, 212Ed:CCP, 212Fa:CCC, 212Fb:CCC, 212Fc:CCC, 212Fd:CCC, 212Ga:CCC, 212Gb:CCC, 212Ha:CCC, 212Hb:CCC, 212Hd:CCC, 212He:CCC, 212Hi:CCP, 212Hj:CCC, 212Hl:CCC, 212Hm:CCP, 212Hn:CCP, 212Ho:CCC, 212Hp:CCP, 212Hq:CCP, 212Hr:CCP, 212Hs:CCC, 212Ht:CCP, 212Hv:CCC, 212Hw:CCC, 212Hx:CCC, 212Ia:CCC, 212Ib:CCP, 212Ja:CCP, 212Jb:CCC, 212Jc:CCC, 212Je:CCP, 212Jf:CCP, 212Jj:CCC, 212Jk:CC?, 212Jl:CCC, 212Jm:CCC, 212Jn:CCC, 212Jo:CCP, 212Jr:CCC, 212Js:CCC, 212Lb:CCC, 212Oa:CCC, 212Oc:CCC, 212Pa:CCC, 221Aa:CCP, 221Ac:CC?, 221Ad:CCP, 221Ae:CCC, 221Af:CCC, 221Ag:CCC, 221Ah:CCC, 221Ai:CCP, 221Ak:CCC, 221Al:CCP, 221Am:CCC, 221Ba:CCC, 221Bb:CCC, 221Bc:CCP, 221Bd:CCC, 221Da:CCC, 221Db:CCC, 221Dc:CCP, 221Ea:CCC, 221Ec:CCC, 221Ed:CCC, 221Ef:CCC, 221Eg:CCC, 221Fa:CCC, 221Fb:CCC, 221Ja:C??, 222De:C??, 222Ek:CCC, 222Em:CCC, 222Hb:CCC, 222Hf:CCC, 222Ia:CCC, 222Ib:CCP, 222Ic:CCP, 222Id:CCP, 222Ie:CCP, 222If:CCP, 222Ja:CCC, 222Je:CCC, 222Jj:CCC, 222Ka:CCC, 222Lb:CCC, 222Lc:CCC, 222Ld:CCC, 231Aa:???, 231Ae:???, 231Ak:???, 231Ap:???, 232Ac:PPP, 232Ad:PP?, 232Ba:P??, M212Aa:CC?, M212Ab:CC?, M212Ac:CCP, M212Ad:CCC, M212Ae:CCC, M212Af:CCC, M212Ba:CCC, M212Bb:CCC, M212Bc:CCC, M212Bd:CCP, M212Ca:CCC, M212Cb:CCC, M212Cc:CCC, M212Cd:CCC, M212Da:CCC, M212Db:CCC, M212Dc:CCC, M212Dd:CCC, M212De:CCC, M212Df:CCC, M212Ea:CCC, M212Eb:CCC, M212Fa:CCC, M212Fb:CCC, M221Aa:CCC, M221Ab:CCP, M221Ac:CCC, M221Ba:CCC, M221Bb:CCC, M221Bc:CCC, M221Bd:CCC, M221Be:CC?, M221Bf:CCP, M221Ca:C??, M221Cb:C??, M221Cc:C??, M221Cd:C??, M221Da:CCC, M221Db:CC?, M221Dc:CCC, M221Dd:CCC

Federal Lands: NPS (Acadia, Great Smoky Mountains, Shenandoah); USFS (Cherokee, George Washington, Jefferson, Pisgah)

Synonymy: Hemlock - Yellow Birch: 24 (Eyre 1980); Hemlock (Braun 1950); Hemlock-Hardwood Forests (Braun 1950); Beech-Hemlock Association (Braun 1928); Tsuga canadensis-Betula alleghaniensis/Rhododendron maximum Forest (Newell et al. 1997); Oak - Hemlock - White Pine Forest (Swain and Kearsley 2001); Hemlock Ravine Community (Swain and Kearsley 2001); Northern Hardwoods - Hemlock - White Pine Forest (Swain and Kearsley 2001); Red Oak - Sugar Maple Transition Forest (Swain and Kearsley 2001); Spruce - Fir - Northern Hardwoods Forest (Swain and Kearsley 2001)

References: Braun 1928, Braun 1950, Eyre 1980, Faber-Langendoen et al. 1996, Kotar et al. 1988, Newell et al. 1997, Swain and Kearsley 2001

Authors: ECS/MCS, RW, East Identifier: A.412

Concept: This hemlock forest of the Central Appalachian Mountains and High Allegheny Plateau occurs on acidic, mesic, sandy loams and sands of glacial till or sandstone in rocky ravines to occasionally flats or moderately steep slopes of any aspect. This is a closed-canopy, late-successional, mixed forest dominated by Tsuga canadensis with associated canopy species including Acer saccharum, Prunus serotina, Betula alleghaniensis, and Fagus grandifolia. Other associates include Acer rubrum, Betula lenta, Carya spp., Pinus strobus, Quercus alba, Quercus rubra, Ulmus americana, and Ostrya virginiana. The variable shrub layer consists of Corylus cornuta, Diervilla lonicera, Hamamelis virginiana, Viburnum lantanoides, and ericaceous species Kalmia latifolia, Rhododendron maximum, and Vaccinium pallidum. The herbaceous layer may include Anemone quinquefolia, Cornus canadensis, Dryopteris carthusiana, Maianthemum canadense, Medeola virginiana, Mitchella repens, Oxalis montana, Trientalis borealis, Trillium grandiflorum, Trillium erectum, and Viola spp. Rhododendron maximum, Sambucus racemosa (= Sambucus pubens), and the abundance of Prunus serotina in the canopy differentiate this from other associations of this alliance.

States/Provinces: MD?, NJ:S1S2, NY:S4, PA:S?, TN:S?, VA?, WV:S?

TNC Ecoregions: 59:C, 60:C, 61:C

USFS Ecoregions: 212Fa:CCC, 212Fb:CCC, 212Fc:CCC, 212Ga:CCC, 212Gb:CCC, 221Ae:CCP, 221Am:CCP, 221Ba:CCP, 221Bd:CCC, 221Dc:CCP, 221E:C?, M212Eb:CCP, M221Ac:CCC, M221Ba:CCC, M221Bb:CCC, M221Bc:CCC, M221Bd:CCC, M221C:C?, M221Da:C??

Synonymy: Eastern hemlock-yellow birch-black cherry forest (CAP pers. comm. 1998)

References: Breden et al. 2001, CAP pers. comm. 1998, Fike 1999

Authors: ECS Confidence: 2 Identifier: CEGL006206 95

Concept: Mixed hemlock - northern hardwood forests of Lower New England / Northern Piedmont. Tsuga canadensis forms at least 50% of the canopy, and associated hardwoods usually include Betula alleghaniensis, Fagus grandifolia, Acer saccharum. This forest is usually described as mesic, but on drier sites, Fagus grandifolia and oaks may also be present in quantity, particularly Quercus rubra. The shrub layer may be dense to fairly open, and often includes Viburnum acerifolium, Acer pensylvanicum. Herbs may be sparse, particularly in dense shade, but often include Medeola virginiana, Oxalis montana, Mitchella repens, Maianthemum canadense, Trientalis borealis, Huperzia lucidula (= Lycopodium lucidulum), and Thelypteris noveboracensis. A bryophyte layer may be well-developed, often characterized by the liverwort Bazzania trilobata. Soils of this community are dry-mesic to mesic and acidic.

Comments: Many stands of this vegetation type in the national forests and Shenandoah National Park have been devastated during the past decade by adelgid-caused tree mortality. In some cases, 100% of the canopy hemlocks have been killed, littering the forest floor with downed wood and stimulating massive increases in understory growth, particularly of Betula spp. and Acer pensylvanicum. Since there is no practical treatment for the adelgid on a landscape level, one can only hope that natural pathogens will emerge to keep the adelgid in check before all of our examples of this community are severely degraded or lost.

Range: This community is generally distributed in large patches from New Hampshire south through New England, becoming more local in the north Atlantic Piedmont and restricted to local patches at higher elevations of the Central Appalachians in Maryland, West Virginia, and Virginia.

States/Provinces: CT:S?, MA:S5, MD:S?, ME:S4, NH:S4, NJ:S3, NY:S4, RI:S?, VA:S?, VT:S4, WV?

TNC Ecoregions: 59:C, 60:C, 61:C, 62:C, 63:C, 64:C

USFS Ecoregions: 212Fa:CCC, 212Fb:CCC, 212Fc:CCC, 212Fd:CCC, 212Ga:CCC, 212Gb:CCC, 221Ae:CCC, 221Af:CCC, 221Ag:CCC, 221Ah:CCC, 221Ak:CCC, 221Am:CCC, 221Ba:CCC, 221Bb:CCC, 221Bc:CCP, 221Bd:CCP, 221Da:CCC, 221Db:CCC, 221Dc:CCP, 222Id:CCP, 232Ad:???, M212Bb:CCC, M212Bc:CCC, M212Cb:CCC, M212Cc:CCC, M212Ea:CCC, M212Eb:CCC, M221Aa:CCC, M221Ab:CC?, M221Ba:CCP, M221Bd:CCC, M221Da:CCC

Federal Lands: NPS (Shenandoah); USFS (George Washington)

Synonymy: Mesic Hemlock-Hardwood Forest (Breden 1989) B, CNE mesic hardwood forest on acidic bedrock/till (Rawinski 1984) B. in part, CNE mesic conifer [transition] forest on acidic bedrock/till (Rawinski 1984) B. in part, CNE dry transitional forest on sandy / gravelly soils (Rawinski 1984), Tsuga canadensis - Betula (alleghaniensis, lenta) / Dryopteris intermedia Forest (Fleming and Coulling 2001), Tsuga canadensis-Betula(all,lenta)-Quercus rubra (NAP pers. comm. 1998), Betula alleghaniensis - Tsuga canadensis / Dryopteris intermedia - Huperzia lucidula Forest (Coulling and Rawinski 1999), Tsuga canadensis - Betula lenta - Betula alleghaniensis Association (Fleming and Moorhead 1996), Tsuga canadensis / Dryopteris intermedia / Bazzania trilobata Association (Rawinski et al. 1994), Liriodendron tulipifera - Betula alleghaniensis / Acer pensylvanicum Association (Rawinski et al. 1994), Eastern Hemlock: 23 (Eyre 1980) B. pro parte, Hemlock - Yellow Birch: 24 (Eyre 1980) B. pro parte, Hemlock Forest (Thompson 1996) B

References: Breden 1989, Breden et al. 2001, Coulling and Rawinski 1999, Edinger et al. 2002, Enser 1993, Eyre 1980, Fleming and Coulling 2001, Fleming and Moorhead 1996, Fleming et al. 2001, Gawler 2002, Metzler and Barrett 2001, NAP pers. comm. 1998, Rawinski 1984, Rawinski et al. 1994, Smith 1983, Sperduto 2000a, Swain and Kearsley 2001, Thompson 1996, Thompson and Sorensen 2000

Authors: G. Fleming and P. Coulling, ECS Confidence: 2 Identifier: CEGL006109

- Maryland Vegetation Classification Subset Report I.C. Mixed evergreen-deciduous forest

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